taghi aliakbari

This article presents a new innovative method to reduce the motions and stabilizing the ships using the ordinary fishing net. The study of ship motions in the waves has been the main concerns of ship designers. Some methods have been used to stabilize the ship in the waves, such as stabilizing tanks, gyro stabilizers and fin stabilizer, which these have their own advantages and disadvantages. In this paper, the study of the net element to reduce the amplitude of Pitch motion in the regular waves in the static state has been done by experiments in a towing tank. The model experiments were performed in the towing tank of National Iranian Marine Laboratory (NIMALA) using two kinds of net with different meshes to compare the effects. The innovative idea of using the fishing net element to reduce the ship motions in the waves was presented for the first time in this research. The findings of this study for the planing craft show a reduction in Pitch motion of up to 20% in regular waves. The length of the model is 2.5 meters and the requirements of the test method are based on the ITTC marine testing instructions.

Sea waves are an important source of environmental energy which can be converted into energy needed for different purposes. In current study, a floating-point absorber (FPA) wave energy converter is simulated, built, and tested. The system is modeled through a two-body system with two degrees of freedom in the heave direction. Modeling hydrodynamic system has been done in ANSYS-AQWA software. In order to obtain the resonance condition and the maximum power of the system, the values of the hydraulic parameters were determined based on optimal PTO coefficients. The experimental data was used to validate the results presented in this paper.

Single point mooring terminals are, as the name implies, facilities of small horizontal dimensions, to which large vessels are moored by means of a bow hawser or by any other means which allows the vessel to rotate 360 around the mooring point. Generally, the single point mooring terminal can have two functions. Primarily, it affords a safe mooring to the vessels. Secondly, it can form a link in the chain for the transport of oil. In this study, with the feasibility of 3D image processing, the SPM translational motion is evaluated. This translational motion includes Surge, Sway, and Heave. In order to ensure the results of the analysis of SPM translational motion, verification is carried out. In the following, by constructing SPM and situating it in reaction condition with regular wave, translational motion is obtained. Finally, the results indicate that image processing is acceptable in translational motion assessment of SPM.

Considering the proper characteristics of the Catamaran floats, such as the surface of the deck, the proper sea keeping, the proper portability of the equipment, the use of these vessels in marine engineering and the various applications of the sea is increasing. Due to the widespread use of these ships, their optimal design has been at the top of the marine research, and in recent years, research has been increasing. In this research, a laboratory model of a Catamaran float with a brittle and breakwater nose, and normal transom shape was constructed in the Persian Gulf marine laboratory and after the calibration of equipment according to the ITTC marine standard and weight, drain and center of gravity adjustment were tested at different speeds.. The results of such surveys on the hydrodynamic parameters of this float and its comparison with the performance of the actual model at sea indicate the desirability of this test, which suggests that the use of these vessels in the future due to its high capability in crossing the waves of the sea will be more widespread. It should be noted that during this research the process of extraction and generalization of the results from the experimental test to the float is explained, which can be a comprehensive guide in this field.

Measurement of resistance force acting on the underwater vehicles has some methods such as numerical method. Because of economical and equipmental reasons the numerical methods has more users than other methods. When this methods has insurance that the result has been validated by experimental results. In this paper, resistance force of spheral body in STAR CCM software has calculated and compare with experimental results that measured by towing tank tests. According to the sphere size and test speed, the flow is in laminar regime, so The result of the CFD Analysis ant towing tank test has validated in this regime.